An ad hoc commission is scheduled to rule on the stand-off between Lille Mayor Martine Aubry and former presidential candidate Ségolène Royal over the leadership of the Socialist Party.

France's feuding Socialists on Monday began examining allegations of fraud in a party leadership vote that saw Martine Aubry, architect of the 35-hour work week, just beat failed presidential candidate Segolene Royal.

Royal is charging that there were irregularities in the vote on Friday to choose a new leader for France's main opposition party and has called for a new ballot.

But on Monday Royal suggested that she was ready to abide by the ruling of a 13-member disputes commission that is to review claims made by both sides.

"I have confidence in this commission," she told France Inter radio.

She noted that commission president Daniel Vaillant was a former interior minister who had experience in tackling election disputes.

The commission is to hand a report to the party's national council ahead of a meeting on Tuesday that is to decide on whether to validate the result.

Aubry, the mayor of Lille, won the vote by a razor-thin margin of 42 votes out of more than 137,000 cast by party members, according to official results announced by the party.

Paris senator David Assouline, a close aide to Royal, said the commission would be asked to examine "dozens" of grievances arising from the vote.

There have been reports that the vote by the party membership was poorly organised, with members in some regions saying they were not told about the runoff called after a first ballot on Thursday failed to produce a clear winner.

The feuding has pushed the already deeply-divided Socialist Party closer to a formal split between the leftist old guard backing Aubry and Royal's centre-left followers.

Royal, eager for a rematch in 2012 with President Nicolas Sarkozy, who defeated her last year, had come out in pole position in the first round of voting on Thursday but without a winning majority.

Third-place contender Benoit Hamon then threw his support behind Aubry after he was knocked out of the race with nearly 23 percent of the vote.

With the dispute dragging, there was talk of an alternative solution.

Deputy Pierre Moscovici, who was considered a contender in the early stages of the race, suggested there should be a "collective leadership" for the coming months to calm the situation.

"The reality is that we really don't know and probably won't know" who won the vote, Moscovici told RTL radio.

He called on outgoing leader Francois Hollande, Royal's former partner, to hold contacts with both sides on such a scenario and said a formal proposal would be discussed by the national council on Tuesday.